[libc++] Allow running the bootstrapping CI build on Darwin

Instead of hard-coding the target for our CI nodes, use the default
compiler triple. Also, allow building compiler-rt for the single
specified triple in case we're running on Darwin (otherwise, the
bootstrapping build complains).

Differential Revision: https://reviews.llvm.org/D113683

diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index f40e3a5..b36f6d7 100755 (executable)
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -475,7 +475,8 @@ bootstrapping-build)
           -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}" \
           -DLLVM_ENABLE_PROJECTS="clang" \
           -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" \
-          -DLLVM_RUNTIME_TARGETS="x86_64-unknown-linux-gnu" \
+          -DLLVM_RUNTIME_TARGETS="$(c++ --print-target-triple)" \
+          -DRUNTIMES_BUILD_ALLOW_DARWIN=ON \
           -DLLVM_ENABLE_ASSERTIONS=ON \
           -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-modules.cmake" \
           -DLIBCXX_TEST_CONFIG="llvm-libc++-shared.cfg.in" \